Modern vehicles are frequently equipped with keyless entry systems or radio keys, what is known as Remote Keyless Entry (RKE). These radio keys control the locking and unlocking of doors and the trunk of a motor vehicle by radio control. In this way, the vehicle door locks of a motor vehicle can be opened and closed wirelessly. Further functions can be activated and deactivated using a radio key, such as the engine immobilizer.
A radio key system comprises a vehicle-based receiver or a vehicle module and one or more mobile transmitters which can be held in the hand, for example. In this case, the transmitter or the portable module may be provided with one or more manually operatable switches. In addition, there are radio keys from newer generations which involve the radio key no longer being taken into the hand, but rather involve the vehicle-based transmitter registering the proximity of the key to the vehicle and unlocking the door lock as a result of the door handle being touched by the driver, for example. Dispensing with manual inputs via the radio key transmitter becomes possible through the use of what is known as bidirectional communication. Unlike in the case of conventional radio key central locking, the radio key transmitter not only sends signals to the locking system but also receives information from the locking system. In this case, the radio key transmitter is in the form of a transceiver. Using what is known as passive start and entry (PASE), the doors unlock simply as a result of the door handle being touched, and the engine can be started at the touch of a button without a key. In this case, the vehicle-based transceiver has a memory which stores an identification code which can identify the radio key transmitter.
The interchange of information with different vehicles which are involved in the traffic and between vehicle and infrastructure can, in future, contribute to increasing the safety of road users and the comfort of the vehicle driver. This communication from vehicle to vehicle and from vehicle to infrastructure, which is subsequently called vehicle-to-X communication (C2X communication), can be used only if a certain proportion of the vehicles or infrastructure units involved are equipped with appropriate communication units which are based on the same technology. Particularly in the case of rapidly changing communication technology and on the basis of the price expectations of the vehicle drivers, the additional outlay—linked to upgrading the vehicles—for providing and installing such a communication unit may be too high. Therefore, simple and inexpensive solution options are needed which can make vehicle-to-X communication available to a large number of vehicle keepers.
In addition, it is known that emergency vehicles such as fire trucks, ambulances or the like are reliant on well-functioning communication when on an assignment. Vehicle-to-vehicle or vehicle-to-control communication techniques are necessary here, in order to be able to transmit messages to other emergency services and to be able to quickly coordinate the rescue operation.
When an emergency call is received at an emergency call center, for example by means of a telephone call, without a precise position statement, the emergency call center sends out emergency services. Frequently, the position statement from the calling parties is not precise enough and the rescue workers first of all need to find the casualties or an object which needs to be sought on site. For this purpose the search parties may have transmitting equipment such as radio telephony available, for example. However, coordination by radio telephony is in practice sometimes inaccurate or does not work or does not work well enough. There is therefore a need for vehicle-to-vehicle communication in the case of emergencies which works reliably.